Self-propelled crane



Sept. 16, 1958 H. SCHEUERPFLUG 2,

SELF-PROPELLED CRANE Filed July so, 1956 INVENTOR 140/25 Jeheuerpf/gf United States Patent SELF-PROPELLED CRANE Hans Scheuerpflug, Nurnberg, Germany, assiguor to Maschinenfabrik Augsburg-Nurnberg, A. G., Nurnberg, Germany Application July 30, 1956, Serial No. 601,082

Claims priority, application Germany July 28, 1955 2 Claims. (Cl. 21258) This invention relates to a self-propelled rotary crane.

The object of the invention is to increase the load capacity in the crane in the direction of the longitudinal axis in the frame of the crane.

A self-propelled rotary crane is designed and dimensioned so that, at maximum load, the limits of stability of the crane and turntable are not exceeded when the boom is positioned crosswise of the longitudinal axis of the frame. Consequently, the full capacity of the crane is not realized when the boom is aligned with the longitudinal axis of the frame.

In accordance with this invention, the boom can be loaded to its full capacity without straining the turntable or the boom. This is done by shifting the pivot bearing of the boom from the rotary chassis mounted on the turntable to a position aligned with the longitudinal axis of the frame. By so doing, the angle between the boom and the retracting cable is increased.

A further feature of the invention lies in the provision of a leg for giving additional support to the frame beneath the pivot bearing thereon.

The means by which the objects of the invention are obtained are described more fully with reference to the accompanying drawing which shows a diagrammatical side elevational view of a crane.

The crane is composed of a conventional boom 1 and retracting cable 2. The lower end of the boom is secured to a pivot bearing 3. The housing for the ing 7 aligned with the longitudinal axis of frame 5. A

leg 9 is positioned beneath bearing 7 in order to give additional support at this point.

In case the crane is to be used for lifting a load beyond its usual capacity, the lower end of the boom is shifted from hearing 3 to bearing 7. Thus the angle a between the normal position of the boom and the retracting cable 2, as shown in the full lines in the drawing, is increased to the angle 13, as shown in broken lines. Consequently, the forces acting on boom 1 and cable 2 are considerably reduced for the same load. Again, the forces acting on boom 1 are no longer transmitted to table 8. As the rotational ability of the crane has been lost by shifting the boom to bearing 7, the mobility of the crane is of little importance. Therefore, the advantage can be taken of this fact by increasing the support for the boom by means of leg 9.

Having now described the means by which the objects of the invention are obtained, I claim:

1. A self-propelled crane comprising a wheeled frame having a longitudinal axis, a housing including hoisting mechanism rotatably mounted on said frame, a boom pivotally secured to said housing, a retracting cable joining said boom to the hoisting mechanism, and a pivot bearing on said frame longitudinally spaced on said axis from the pivotal securement of said boom to said housing for mounting said boom on said frame with an increase in the angle between said boom and said retracting cable.

2. A self-propelled crane as in claim 1, further comprising leg means for supporting said frame directly below said pivot bearing.

References Cited in the file of this patent UNITED STATES PATENTS 330,870 Case Nov. 24, 1885 1,598,897 Tirrell Sept. 7, 1926 2,131,479 McGitfert et a1 Sept. 27, 1938 2,602,552 Orlolf July 8, 1952 

